To more fully elaborate the clinical, cultural, histochemical, biochemical, ultrastructural, electrophysiologic and immunologic abnormalities of patients with the various myopathies and certain other neuromuscular disorders. To further sub-classify patients in each category using those parameters. To seek pathogenic mechanisms, using a variety of different techniques including tissue culture and ones listed above, applied to the patient's body fluids and tissues, especially to the muscle biopsy specimens. To treat myopathic disorders by different methods in order to learn which is most effective within each disease category. To produce animal models of pathogenic phenomena. BIBLIOGRAPHIC REFERENCES: Askanas, V., Engel, W. K., Britton, D. E., Adornato, B. T. and Eiben, R. M.: An unusual mitochondrial abnormality reincarnated ex aegro and induced de novo in cultured muscle fibers. Neurology, 27: 348, 1977. Askanas, V., Engel, W. K., Ringel, S. P. and Bender, A. N.: Acetylcholine receptors (AChR) in aneurally cultured human and animal skeletal muscle fibers. Neurology, 1977, in press.